As the semiconductor processing industry strives for larger production yields while increasing the number of circuits per unit area, attention has been focused on the continued development of reliable high-resolution patterning techniques. One such technique in use today is commonly referred to as imprint lithography. Imprint lithography processes are described in detail in numerous publications, such as U.S. Patent Application Publication No. 2004/0065976, U.S. Patent Application Publication No. 2004/0065252, and U.S. Pat. No. 6,936,194, all of which are incorporated by reference herein. Other areas of development in which imprint lithography has been employed include biotechnology, optical technology, mechanical systems, and the like.
An imprint lithography technique disclosed in each of the aforementioned U.S. patent application publications and patent includes formation of a relief pattern in an imprint resist and transferring a pattern corresponding to the relief pattern into an underlying substrate. The patterning process uses a template spaced apart from the substrate and a polymerizable composition disposed between the template and the substrate. The polymerizable composition (or imprint resist) is solidified to form a layer that has a pattern conforming to a shape of the surface of the template that contacts the polymerizable composition. After solidification, the template is separated from the patterned layer such that the template and the substrate are spaced apart.
In some cases, portions of the solidified imprint resist adhere to the template, and can result in separation defects in the patterned layer as well as defects in subsequent patterned layers formed with the same template. Efforts to reduce separation defects related to adherence of solidified imprint resist on the template include formation of a release layer on the surface of the template before imprinting to modify the surface energy of the template. These previously applied release layers, such as one formed by treatment of the template with tridecafluoro-1,1,2,2-tetrahydrooctyl dimethylchlorosilane, typically degrades with use. As the previously applied release layer degrades, subsequent separation of the template from the solidified imprint resist can become increasingly more difficult (e.g., as the number of successive imprints increases in a step-and-repeat process), contributing to the introduction of separation defects in the imprinted patterns and reducing the number of successive imprints that can be made with the template.